You create an area of frigid cold which blasts an area for an instant and continues to grip those affected by it.

Each creature within a 6m radius Sphere, centred on a point you can see within range must make a Constitution saving throw, taking 7d10 Ice damage and receives levels of

Brittle

Critical Success (+10). The target is unaffected.
Success. The target takes half damage and received 2 levels of Brittle. These levels of Brittle are reduced by 1 at the end of each of their turns.
Failure. The target takes full damage and receives 4 levels of Brittle. These levels of Brittle are reduced by 1 at the end of each of their turns.
Critical Failure (–10). as failure, except the target takes 1.5× damage.

Creatures that fail also have their actions slowed as the arctic wind takes hold. Their speed is reduced by 4m, they are unable to take reactions, they have Disadvantage on Attack Rolls, Dexterity ability checks, Dexterity saving throws, and Death saving throws; and attacks made against the creature automatically hit if the attacker is within 4m of them. At the end of each of its turns, an affected creature can make a Constitution saving throw to end this effect on them.

A creature that is killed while affected by this spell becomes encased in black, see-through ice 30cm thick. The ice is magickal, and is impervious to spells below 9th level (excluding spells such as Dispel and Anti-magick Field, or similar), has 30 HP, has an AC of 25, and a damage threshhold of 20.